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Review of 2011 studies and priorities for 2012

Review of 2011 studies and priorities for 2012. LIU-SPS-BD. Main results from 2011 ( B. Goddard, LIU-SPS, 7.12.2011). LHC can digest half-nominal transverse emittance SPS can deliver nominal 25 ns intensity in ~3 um, and almost ultimate 50 ns intensity in 2 um

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Review of 2011 studies and priorities for 2012

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  1. Review of 2011 studies and priorities for 2012 LIU-SPS-BD

  2. Main results from 2011(B. Goddard, LIU-SPS, 7.12.2011) • LHC can digest half-nominal transverse emittance • SPS can deliver nominal 25 ns intensity in ~3 um, and almost ultimate 50 ns intensity in 2 um • Smaller emittances in SPS for 50 and 25 ns beams • (Where) has the e-cloud gone? • E-cloud mitigation industrialisation works • Q20 optics deployment progress • Q20 instability limits progress • PS-SPS longitudinal transfer studied • Limits still there from MKE heating and ZS sparking • BI upgrades are not for overnight • Transverse emittance measurement crucial, but still shaky • High bandwidth feedback needs kick-start for implementation

  3. Discussion points • Brightness: • Can we draw all the limitation curves in the intensity-emittance diagram for 25 and 50 ns?Do we know by how much the upgrades will move them?? • Smaller emittances in 2011: • Are we confident this is a real change, or the BI ‘improvements’? (LHC emittances confirm 2 – 2.5 um from SPS, but what was in 2010?) • E-cloud in 2011 • Where has it gone? • Q20 optics: • Are results for single- and multi-bunch beams as expected (emittances, instabilities, losses, RF)? • PS-SPS longitudinal transfer • What are the implications of the results on capture losses?

  4. E-cloud in 2011 (B. G.) • Where has it gone? • What SEY values are consistent with observed thresholds? • Are these SEY values explainable from ‘operational’ 50 ns scrubbing? • Saw this for LHC where initial 25 ns injection was much easier than 50 ns • What are the essential things to demonstrate in 2012? • Scrubbing test period • Effective scrubbing with lower average beam power? • Quantification of SEY values and ecloud density • Measurement techniques (stable phase??) • Performance reach for 25 ns beams • Mitigation measure tests • Validation of coated dipoles with in-situ monitors • Understand vacuum pressure at coated dipoles – theoretical progress? Desorption? • Removal of coatings, magnet measurement of coated dipoles, ... • Big decision to make at end of 2012..coat or scrub. • High bandwidth feed-back: need urgently to define project plan in detail

  5. Limits from MKE and ZS (B. G.) • MKE heating should cease to be a limit for 2014 • Any detailed impedance measurements planned to check differences 2011-2012? • ZS sparking problematic for ‘operatically driven’ intensity increases • Modulation of voltage on PPM basis for ion traps only • Negative bump at ZS not tested – plan for 2012? • Longer term – not much prospect of major improvement • Should we plan new filling schemes for these ‘total intensity’ limits (e.g. 3 batches only?!) • What about longer bunches or more bunch shape control?

  6. Q20 optics • Excellent results for • single bunch stability and emittances • multi-bunch LHC beams (1.8 x1011 at 450 GeV for 50 ns beam!) • need to set-up: controlled longitudinal emittance blow-up • working point optimisation (“space charge” limit) • dedicatedoptimisation and studies in 2012 for Q20 • how many efforts should still go to Q26? • When we will be ready to inject to LHC? • transfer lines • capture losses in LHC - MDs • batch-by-batch longitudinal emittance blow-up in the LHC (could be feasible, but not very clean – P. Baudrenghien)? • Other SPS cycles: ions, FT&CNGS, LHC pilot?

  7. Priorities for 2012 • Test scrubbing as e-cloud mitigation • Q20 multi-bunch injected to LHC, tested for other cycles – different MD scheme (H.B.)? • Push up intensity for 25 ns beam (Q20?) to see possible limitations – the way to go after LS1 (clear message from LHC experiments about role of pile-up) • Double RF system • stability • controlled emittance blow-up • Impedance identification (reference measurements < LS1) =>

  8. Priorities for 2012 • Test scrubbing as e-cloud mitigation • Q20 multi-bunch injected to LHC, tested for other cycles – different MD scheme (H.B.)? • Push up intensity for 25 ns beam (Q20?) to see possible limitations – the way to go after LS1 (clear message from LHC experiments about role of pile-up) • Double RF system • stability • controlled emittance blow-up • Impedance identification (reference measurements < LS1) => Happy New Year!

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